The present invention relates to copying machines in general, especially to photographic copying machines, and more particularly to improvements in copying machines of the type wherein any one of a series of masks, each having a differently dimensioned and/or configurated light-transmitting opening, can be inserted into or placed onto the machine to determine the format of reproductions and/or that portion or those portions of an original whose image is to be reproduced.
It is known to provide a photographic copying machine with a plurality of holders having different light-transmitting openings for different formats of originals, e.g., for small, medium-sized or large film frames. As a rule, each holder carries or embodies indicia whose number and/or distribution is indicative of the size and/or configuration of the respective opening. The indicia serve to actuate electric switches or analogous elements which, in turn, adjust the copying machine for proper reproduction of images of originals whose format determines the selection of a particular holder. A holder will be replaced by a different holder when the copying of smaller originals is to be followed by copying of larger originals, or when the machine is to make enlargements of smaller or larger portions of originals having one and the same size.
It is also known to employ shiftable strip- or web-like masks which overlie the photographic paper at the copying station and to properly adjust the exposure controls of the copying machine in automatic response to shifting of the masks. Automatic shifting of a web or band of masks must be carried out in dependency on the format of the originals. To this end, German Pat. No. 1,209,871 proposes to provide the masks for originals with indicia in the form of recesses or bores which can receive spring-biased pin-shaped movable portions of electric switches. The switches are connected with an evaluating circuit which adjusts the exposure controls as a function of the number and/or distribution of switches which are actuated by a selected mask. A drawback of such proposal is that the evaluating circuit is expensive, complex and sensitive. Moreover, the automatic system is rather bulky which presents problems because the system must be installed in or on that portion of a copying machine where the space is at a premium.